read and write are fully implemented, and always use
streaming mode. The I/O bases on the buffered access layer
provided by Plasma_client, and so it is a good idea to
configure some number of buffers to use, with
Plasma_client.configure_buffer.

Arguments:

repl: The replication factor for new files. Defaults to 0, i.e.
to the server default.

verbose: Whether to output progress messages to stderr for
all metadata modifications.
Defaults to false. (This exists for the command-line utility
plasma.)